DATA SHEE T
Am79C875
NetPHY 4LP Low Power Quad 10/100-TX/FX Ethernet Transceiver
DISTINCTIVE CHARACTERISTICS
Four 10/100BASE-TX Ethernet PHY transceivers Automatic Polarity Detection during Auto-
Negotiation and 10BASE-T signal reception
Supports RMII (Reduced MII) interface
Unique scramble seed per port reduces EMI in
125 meter (m) MLT-3 and Baseline Wander
switch and repeater applications
operation
One port supports 100BASE-FX function
Low power consumption
Supports Inter Packet Gap as low as 40 ns for
1.3 Watt (W) typical (1:1 magnetics)
high throughput applications
1.2 W typical (1.25:1 magnetics)
No external filters or chokes required
Power management modes:
Compliant with IEEE 802.3 standards for
Selectable 1:1 or 1.25:1 transmit transformer
100BASE-TX, 100BASE-FX, and 10BASE-T
Unplugged - approximately 100 mW per port
Built-in loopback and test modes
Power Down - approximately 3 mW per port
Small 14 x 20 mm 100-pin PQR package
Single 3.3 V power supply with 5 V I/O tolerance
Small package allows side-by-side PHY layout
Patent-pending DC restoration technique
reduces baseline wander susceptibility Fits neatly behind quad magnetics
Full and half-duplex operation with full-featured Saves board space over larger 208 PQFP
Auto-Negotiation function packages
Next Page register support Support for Industrial Temperature
(-40C to +85C)
GENERAL DESCRIPTION
The NetPHY 4LP device is a highly integrated, low rectly to the MAC and TX/RX media pins are routed di-
power 10BASE-T/100BASE-TX/FX Quad Ethernet rectly to the magnetics. Direct routing of high speed
transceiver. The NetPHY 4LP device includes traces is imperative for project system design and EMI
integrated RMII, ENDECs, Scrambler/Descrambler, noise reduction.
and full-featured Auto-Negotiation with support for Par-
The NetPHY 4LP devices on-chip input filtering and
allel Detection and Next Page. Port 3 can be config-
output waveshaping eliminates the need of external hy-
ured as a 100BASE-FX transmitter to output an NRZI
brid filters for media connection. Integrated LED logic
PECL level signal. Each receiver has an adaptive
allows three LEDs per port to be driven directly. These
equalizer/DC restoration circuit for accurate clock/data
features greatly simplify the design of a 100BASE-X re-
recovery on the 100BASE-TX signal at different cable
peater/switch board, thus requiring minimum external
lengths and can perform to 125 m and beyond.
components.
The NetPHY 4LP device operates on a 3.3 V supply
For ease of system and chip setup and testing, the Net-
and offers 5 V I/O tolerance for mixed signal designs.
PHY 4LP device offers loopback and various ad-
Power consumption is 1.3 W typical for the device, or
vanced testing and monitoring capabilities.
0.3 W per port using 1:1 magnetics. The NetPHY
4LP device can use 1.25:1 magnetics, which de- The NetPHY 4LP device is available in the Commer-
creases transmit power consumption and reduces de- cial (0C to 70C) or Industrial (-40C to +85C) tem-
vice power consumption to 1.2 W typical. perature ranges. The Industrial temperature range is
well suited to environment such as enclosures with re-
The NetPHY 4LP device offers an optimized pinout
stricted air flow or outdoor equipment.
for network applications. RMII pins can be routed di-
Publication# 22236 Rev: I Amendment/0
Issue Date: September 2005
Refer to AMDs Website (www.amd.com) for the latest information.BLOCK DIAGRAM (PER PORT)
100TX
PCS PMA TP_PMD
Framer Clock Recovery MLT-3
TX+
Carrier Detect Link Monitor BLW
4B/5B Signal Detect Stream Cipher
100RX TX-
RMII Data
25 MHz
Interface
Mux
Interface
10TX
10BASE-T
Transformer
10RX
MAC
RX+
RX-
MDC/MDIO Control/Status 20 MHz
RX FLP
MII Serial Management PLL Clk Generator Auto-
25 MHz
Interface and Registers Test LED Control Negotiation
PHYAD[4:0] REFCLK TEST LED
[3:0] Drivers
22236G-1
2 Am79C875